In resent years, in portable electronic devices and the like, the reduction in the size, thickness and weight of electronic devices, and the high-density mounting of semiconductor devices have been strongly demanded. Furthermore, with the high integration of semiconductor elements caused by the progress of micro-fabrication technology, a technology known as a chip-mounting technology wherein semiconductor elements, such as chip-size packages and bear chips are directly mounted has been proposed. Such trends are also seen in optical devices, and various configurations have been disclosed.
For example, as in a sectional view of a conventional solid-state image device shown in FIG. 16, an element structure and a method for manufacturing such an element structure for realizing the reduction in the thickness and manufacturing costs of a solid-state image device 100 by directly adhering a transparent member 102 using a low-refractive-index adhesive 103 onto micro lenses 104 in an imaging region 105 of a solid-state image element 101 in the solid-state image device 100 have been disclosed.
The method is a method wherein the micro lenses 104 are directly formed on the solid-state image element 101 having the imaging region 105, and the transparent member 102 is directly adhered on the micro lenses 104 maintaining parallelism to the imaging region 105. At this time, by filling the low-refractive-index adhesive 103 between the micro lenses 104 and the transparent member 102 without a gap therebetween, electrical properties and optical properties are secured, and reliability is also secured, even if there is change in environmental conditions for using the solid-state image device 100. In the solid-state image device 100, the transparent member 102 is directly adhered on the micro lenses 104 on the solid-state image element 101 to protect the solid-state image element 101. Therefore, no air region wherein neither resin nor the like is filled between the micro lenses 104 and the transparent member 102, which is a part of the package, is present, and a region from the bottom surface of the solid-state image element 101 to the transparent member 102 can be mounted on the circuit module and the like as the thickness of the solid-state image device 100. As described above, since the solid-state image device 100 can be directly mounted in the circuit module and the like without using a ceramic package equipped with a glass lid, the thin solid-state image device 100 has been realized at low manufacturing costs.
A method for manufacturing another conventional solid-state image device of another configuration will be described referring to FIG. 17.
FIG. 17 is a step sectional view showing a conventional method for manufacturing a solid-state image device.
First, a plurality of solid-state image elements 111 are aligned and adhered on a surface of a substrate 110 with imaging regions thereof facing up at specified intervals as shown in FIG. 17A; the imaging region of each of the solid-state image elements 111 is coated with a flexible protective film 112 individually formed as shown in FIG. 17B; and the solid-state image elements 111 coated with the protective films 112 are compressed by a mold having flat compressing surfaces together with the substrate 110, and gaps surrounded by the compressing surfaces of the mold, the protective films 112 and the adjacent solid-state image elements 111 are filled with a molding resin 113 for resin molding as shown in FIGS. 17C and 17D. Then, the protective films 112 are removed from the imaging regions of the solid-state image elements 111 as shown in FIG. 17E; a transparent member 114 is adhered on the entire surface of the substrate 110 so as to coat the imaging region of each of the solid-state image elements 111 via the molded molding resin 113 as shown in FIG. 17F; and the solid-state image elements 111 are cut along the boundaries with the adjacent solid-state image elements 111 to form isolated solid-state image devices 115 as shown in FIG. 17G to realize cost reduction.
However, in the solid-state image device shown in FIG. 16, since a peripheral circuit region 107 including electrode pads 106 on the solid-state image elements 101 is not protected, the peripheral circuit region 107 must be individually molded with, for example, a liquid resin after being mounted on the circuit substrate using wire bonding or the like, and cost reduction is difficult.
Furthermore, when the transparent member 102 is directly adhered on the micro lenses 104 on the solid-state image element 101 with the adhesive 103, the adhesive 103 disadvantageously flows into the electrode pads 106 of terminal electrodes outside the imaging region 105 on the solid-state image element 101 to coat the electrode pads 106, resulting in the difficulty of bonding.
There was also a case in which moisture disadvantageously enters from the adhered boundary between the solid-state image element 101 and the transparent member 102, lowering moisture resistance.
In the solid-state image device shown in FIG. 17, although peripheral circuit regions including electrode pads and bonding wires of the solid-state image element 111 are collectively molded by transfer molding with the molding resin 113, since the protective film 112 is directly adhered on the imaging region of the solid-state image element 111 before molding and the protective film 112 is removed after molding, a gap 116 is left between the solid-state image element 111 and the transparent member 114 after removing the protective film 112 resulting in the difficulty of the thickness reduction of the solid-state image device 115.
Since the gap 116 is formed on the imaging region of the solid-state image element 111 as shown in FIG. 17G after removing the protective film 112, the strength of the solid-state image element 111 is disadvantageously lowered.
If the resin of the protective film 112 remains between micro lenses of the solid-state image element 111 when the protective film 112 is removed, it is difficult to discharge the remaining resin from the gap 116, leading to the lowering of long-term reliability.
Furthermore, molding must be carried out so that the bonding wires are buried in the molding resin 113, resulting in the difficulty of thickness reduction.
To solve the above problems, an object of the present invention is to provide a small, thin and high-quality optical device that excels in moisture resistance and prevents deterioration of strength, and a method for manufacturing such an optical device; and a camera module and an endoscope module equipped with such an optical device.